|The structure of the benthic macrofauna collected across a transect at the central chile shelf and relationships with giant sulfur bacteria Thioploca spp. mats.|
Carrasco, F.D.; Gallardo, V.A.; Baltazar, M. (1999). The structure of the benthic macrofauna collected across a transect at the central chile shelf and relationships with giant sulfur bacteria Thioploca spp. mats. Cah. Biol. Mar. 40(2): 195-202
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
|Authors|| || Top |
- Carrasco, F.D.
- Gallardo, V.A.
- Baltazar, M.
The analysis of the community structure of macrobenthic (>0.25 mm) assemblages collected from a transect in the Central Chile shelf and the relationships with sulphur bacteria Thioploca spp. was performed. Samples were obtained in April 1982 (southern Autumn) with a 0.1 m2 Smith-McIntyre grab at three cross-shelf stations off Concepcion Bay, central Chile. Sediments consisted of fine muds (>95% silt-clay) with high (>15%) total organic matter. Here bottom waters showed the typical characteristics of the pole-ward flowing Sub-Surface Equatorial Waters, i.e., higher salinity than those at surface (>34.5%,) and low oxygen (<1.0 ml O-2 l-1r). Filaments of the giant bacteria Thioploca spp. were moderately collected at station E I (31.9 g m-2 wet weight at 75 m depth), were scarce at station E2 (2.3 g m-2 w. wt. at 100 m), and absent at station E3 (121 m). In all sites macrofaunal composition was comparable, with a low total species richness, a low species diversity (27 species), and a high dominance. Average figures for abundance ranged from 77,880 ind m-2 at El to 14,770 ind m-2 at E3. Faunal biomass (w. wt.) ranged from I 10 g m-2) at El to 32 g m-2 at E3. Polychaeta was the most abundant taxon (78% of the total), with Paraprionospio pinnata as the dominant species in all stations. Statistical analyses indicated significant differences among all sites, but in particular between El, with a larger population of Thioploca spp., and the deeper E2 and E3 sites where Thioploca was scarse and absent, respectively.